U.S. patent application number 12/431834 was filed with the patent office on 2010-11-04 for fatty ester containing photoconductors.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to Jin Wu.
Application Number | 20100279216 12/431834 |
Document ID | / |
Family ID | 43030623 |
Filed Date | 2010-11-04 |
United States Patent
Application |
20100279216 |
Kind Code |
A1 |
Wu; Jin |
November 4, 2010 |
FATTY ESTER CONTAINING PHOTOCONDUCTORS
Abstract
A photoconductor that includes, for example, a supporting
substrate, a photogenerating layer, and a charge transport layer,
and wherein the photogenerating layer contains a vulcanized fatty
ester.
Inventors: |
Wu; Jin; (Webster,
NY) |
Correspondence
Address: |
PATENT DOCUMENTATION CENTER;XEROX CORPORATION
100 CLINTON AVE SOUTH, MAILSTOP: XRX2-020
ROCHESTER
NY
14644
US
|
Assignee: |
XEROX CORPORATION
Norwalk
CT
|
Family ID: |
43030623 |
Appl. No.: |
12/431834 |
Filed: |
April 29, 2009 |
Current U.S.
Class: |
430/58.8 ;
430/59.1; 430/59.4; 430/59.5 |
Current CPC
Class: |
G03G 5/047 20130101;
G03G 5/0514 20130101; G03G 5/14721 20130101; G03G 5/0503 20130101;
G03G 5/051 20130101 |
Class at
Publication: |
430/58.8 ;
430/59.1; 430/59.4; 430/59.5 |
International
Class: |
G03G 5/06 20060101
G03G005/06; G03G 15/02 20060101 G03G015/02; G03G 5/047 20060101
G03G005/047 |
Claims
1. A photoconductor comprising a supporting substrate, a
photogenerating layer, and at least one charge transport layer, and
wherein said photogenerating layer includes a vulcanized fatty
ester.
2. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is present in said photogenerating layer in
an amount of from about 0.1 to about 30 weight percent.
3. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is present in said photogenerating layer in
an amount of from about 1 to about 20 weight percent wherein at
least one charge transport layer is 1 layer, 2 layers, or 3
layers.
4. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is present in said photogenerating layer in
an amount of from about 3 to about 10 weight percent, and wherein
said at least one charge transport layer is 1 or 2 layers.
5. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is generated from the reaction of an
unsaturated fatty ester and a sulfur source.
6. A photoconductor in accordance with claim 5 wherein said
unsaturated fatty ester is selected from the group consisting of
corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil,
palm oil, peanut oil, coconut oil, rapeseed oil, safflower seed
oil, sesame seed oil, soybean oil, sunflower seed oil, tallow, and
optionally mixtures thereof.
7. A photoconductor in accordance with claim 5 wherein said sulfur
source is selected from the group consisting of elemental sulfur,
sulfur monochloride, sulfur dichloride, sodium sulfide, and sodium
polysulfide.
8. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is selected from the group consisting of
sulfurized corn oil, sulfurized canola oil, sulfurized cottonseed
oil, sulfurized grapeseed oil, sulfurized olive oil, sulfurized
palm oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized
rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil,
sulfurized sunflower seed oil, sulfurized tallow, sulfurized fish
oil, and mixtures thereof.
9. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester possesses a sulfur content of from about 5
to about 40 weight percent.
10. A photoconductor in accordance with claim 1 wherein said
photogenerating layer is comprised of at least one photogenerating
pigment, a polymer, and said vulcanized fatty ester present in an
amount of from about 1 to about 8 weight percent.
11. A photoconductor in accordance with claim 1 wherein said charge
transport layer is comprised of ##STR00007## wherein X is selected
from the group consisting of alkyl, alkoxy, aryl, and halogen, and
mixtures thereof, and wherein at least one charge transport layer
is from 1 to about 4.
12. A photoconductor in accordance with claim 11 wherein said alkyl
and said alkoxy each contains from about 1 to about 12 carbon
atoms, and said aryl contains from about 6 to about 36 carbon
atoms; and wherein said vulcanized fatty ester is present in an
amount of from about 1 to about 5 weight percent.
13. A photoconductor in accordance with claim 11 wherein said aryl
amine is
N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine.
14. A photoconductor in accordance with claim 1 wherein said charge
transport layer is comprised of ##STR00008## wherein X, Y, and Z
are independently selected from the group consisting of alkyl,
alkoxy, aryl, and halogen, and mixtures thereof.
15. A photoconductor in accordance with claim 1 wherein said charge
transport includes a component selected from at least one of the
group consisting of
N,N'-bis(4-butylphenyl)-N,N'-di-p-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-m-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-o-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4''--
diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2-ethyl-6-methylphenyl)-[p-terp-
henyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4''-
-diamine,
N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine- ,
and
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[p-terphenyl]-4,4''-diamine;
and wherein said at least one charge transport layer is from 1 to
3, and said vulcanized fatty ester is present in an amount of from
about 1 to about 10 weight percent.
16. A photoconductor in accordance with claim 1 further including
in at least one of said charge transport layers an antioxidant
comprised of a hindered phenolic, a hindered amine, and mixtures
thereof, and said at least one charge transport layer is one layer,
two layers, or three layers.
17. A photoconductor in accordance with claim 1 wherein said
photogenerating layer is comprised of an at least one
photogenerating pigment.
18. A photoconductor in accordance with claim 17 wherein said
photogenerating pigment is comprised of at least one of a titanyl
phthalocyanine, a hydroxygallium phthalocyanine, a halogallium
phthalocyanine, a perylene, or mixtures thereof.
19. A photoconductor in accordance with claim 17 wherein said
photogenerating pigment is comprised of a metal phthalocyanine, a
metal free phthalocyanine, or mixtures thereof.
20. A photoconductor in accordance with claim 17 wherein said
photogenerating pigment is comprised of a hydroxygallium
phthalocyanine.
21. A photoconductor in accordance with claim 1 further including a
hole blocking layer, and an adhesive layer, and wherein said
vulcanized fatty ester is present in an amount of from about 2 to
about 10 weight percent.
22. A photoconductor in accordance with claim 1 wherein said at
least one charge transport layer is from 1 to about 4 layers.
23. A photoconductor in accordance with claim 1 wherein said at
least one charge transport layer is comprised of a top charge
transport layer and a bottom charge transport layer, and wherein
said top layer is in contact with said bottom layer and said bottom
layer is in contact with said photogenerating layer, and wherein
said vulcanized fatty ester is selected from the group consisting
of sulfurized corn oil, sulfurized canola oil, sulfurized
cottonseed oil, sulfurized grape seed oil, sulfurized olive oil,
sulfurized palm oil, sulfurized peanut oil, sulfurized coconut oil,
sulfurized rapeseed oil, sulfurized sesame seed oil, sulfurized
soybean oil, sulfurized sunflower seed oil, sulfurized tallow,
sulfurized fish oil, and mixtures thereof.
24. A photoconductor comprising a supporting substrate, a
vulcanized fatty ester containing photogenerating layer, and a
charge transport layer, and wherein said photogenerating layer
comprises a photogenerating component and said fatty ester.
25. A photoconductor comprising a photogenerating layer, and at
least one charge transport layer, and wherein said photogenerating
layer is comprised of at least one photogenerating pigment and a
fatty ester, and wherein said fatty ester is present in an amount
of from about 1 to about 12 weight percent, and said at least one
charge transport layer is 1, 2, or 3 layers.
26. A photoconductor in accordance with claim 1 wherein said
vulcanized fatty ester is selected from the group consisting of
sulfurized corn oil, sulfurized canola oil, sulfurized cottonseed
oil, sulfurized grape seed oil, sulfurized olive oil, sulfurized
palm oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized
rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil,
sulfurized sunflower seed oil, sulfurized tallow, sulfurized fish
oil, and mixtures thereof.
27. A photoconductor in accordance with claim 25 wherein said
vulcanized fatty ester is selected from the group consisting of
sulfurized corn oil, sulfurized canola oil, sulfurized cottonseed
oil, sulfurized grape seed oil, sulfurized olive oil, sulfurized
palm oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized
rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil,
sulfurized sunflower seed oil, sulfurized tallow, and sulfurized
fish oil.
28. A photoconductor in accordance with claim 25 wherein said fatty
ester is generated by the reaction of an unsaturated fatty ester
and a sulfur source, and wherein said unsaturated fatty ester is
selected from the group consisting of corn oil, canola oil,
cottonseed oil, grape seed oil, olive oil, palm oil, peanut oil,
coconut oil, rapeseed oil, safflower seed oil, sesame seed oil,
soybean oil, sunflower seed oil, tallow, and optionally mixtures
thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Copending U.S. application Ser. No. 12/059,573 (Attorney
Docket No. 20070644-US-NP), filed Mar. 31, 2008, entitled
Oxadiazole Containing Photoconductors, the disclosure of which is
totally incorporated herein by reference, illustrates a
photoconductor comprising a supporting substrate, a photogenerating
layer, and at least one charge transport layer wherein at least one
of the charge transport layers is comprised of at least one charge
transport component, and wherein at least one of the
photogenerating layer, and the charge transport layer includes an
oxadiazole.
[0002] In U.S. application Ser. No. 11/472,765, filed Jun. 22,
2006, U.S. Publication No. 20070298341 (Attorney Docket No.
20060288-US-NP), and U.S. Pat. No. 7,485,398, the disclosures of
which are totally incorporated herein by reference, there are
disclosed, for example, photoconductors comprising a
photogenerating layer and a charge transport layer, and wherein the
photogenerating layer contains a titanyl phthalocyanine prepared by
dissolving a Type I titanyl phthalocyanine in a solution comprising
a trihaloacetic acid and an alkylene halide; adding the mixture
comprising the dissolved Type I titanyl phthalocyanine to a
solution comprising an alcohol and an alkylene halide thereby
precipitating a Type Y titanyl phthalocyanine; and treating the
Type Y titanyl phthalocyanine with a monohalobenzene.
[0003] High photosensitivity titanyl phthalocyanines are
illustrated in copending U.S. application Ser. No. 10/992,500, U.S.
Publication No. 20060105254 (Attorney Docket No. 20040735-US-NP),
the disclosure of which are totally incorporated herein by
reference, which, for example, discloses a process for the
preparation of a Type V titanyl phthalocyanine, comprising
providing a Type I titanyl phthalocyanine; dissolving the Type I
titanyl phthalocyanine in a solution comprising a trihaloacetic
acid and an alkylene halide like methylene chloride; adding the
resulting mixture comprising the dissolved Type I titanyl
phthalocyanine to a solution comprising an alcohol and an alkylene
halide thereby precipitating a Type Y titanyl phthalocyanine; and
treating the Type Y titanyl phthalocyanine with monochlorobenzene
to yield a Type V titanyl phthalocyanine.
[0004] A number of the components and amounts thereof of the above
copending applications, such as the supporting substrates, resin
binders, photogenerating layer components, such as hydroxygallium
phthalocyanines, titanyl phthalocyanines, antioxidants, charge
transport components, hole blocking layer components, adhesive
layers, and the like, may be selected for the members of the
present disclosure in embodiments thereof.
BACKGROUND
[0005] This disclosure is generally directed to members like
xerographic imaging members; photoreceptors, photoconductors, and
the like. More specifically, the present disclosure is directed to
rigid, multilayered flexible, belt imaging members, or devices
comprised of an optional supporting medium like a substrate, a
fatty ester, and more specifically, a vulcanized fatty ester
photogenerating layer, and a charge transport layer including a
plurality of charge transport layers, such as a first charge
transport layer and a second charge transport layer, an optional
adhesive layer, an optional hole blocking or undercoat layer, and
an optional overcoating layer. At least one in embodiments refers,
for example, to one, to from 1 to about 10, to from 2 to about 7;
to from 2 to about 4, to two, and the like. Moreover, the fatty
ester can be added to the photogenerating layer instead of being
dissolved in the photogenerating layer solution.
[0006] Yet more specifically, there is disclosed a photoconductor
comprised of a supporting substrate, a vulcanized fatty ester, such
as, for example, those esters as illustrated hereinafter,
containing photogenerating layer, a charge transport layer, or
charge transport layers, such as a first pass charge transport
layer, a second pass charge transport layer to primarily permit
excellent and minimal undesirable ghosting characteristics, reduced
paper edge ghosting (PEG), as compared to a photoconductor that
does not contain the fatty ester; excellent photoconductor
photosensitivities, and an acceptable, and in embodiments a low
V.sub.r; and minimization or prevention of V.sub.r cycle up.
[0007] The photoconductors disclosed herein possess a number of
advantages, such as in embodiments, the minimization of undesirable
ghosting on developed images, such as xerographic images, including
improved ghosting at various relative humidities; excellent cyclic
and stable electrical properties; minimal charge deficient spots
(CDS); compatibility with the photogenerating and charge transport
resin binders; and acceptable lateral charge migration (LCM)
characteristics, such as for example, excellent LCM resistance.
[0008] Ghosting refers, for example, to when a photoconductor is
selectively exposed to positive charges in a number of xerographic
print engines when some of the charges enter the photoconductor and
manifest themselves as a latent image in the next printing cycle.
This print defect can cause a change in the lightness of the half
tones, and is commonly referred to as a "ghost" that is generated
in the previous printing cycle. An example of a source of the
positive charges is the stream of positive ions emitted from the
transfer corotron. Since the paper sheets are situated between the
transfer corotron and the photoconductor, the photoconductor is
shielded from the positive ions from the paper sheets. In the areas
between the paper sheets, the photoconductor is fully exposed, thus
in this paper free zone the positive charges may enter the
photoconductor. As a result, these charges cause a print defect or
ghost in a half tone print if one switches to a larger paper format
that covers the previous paper print free zone.
[0009] Excellent cyclic stability of the photoconductor refers, for
example, to almost no or minimal change in a generated known
photoinduced discharge curve (PIDC), especially no or minimal
residual potential cycle up after a number of charge/discharge
cycles of the photoconductor, for example about 100 kilocycles, or
xerographic prints of, for example, from about 80 to about 100
kiloprints. Excellent color print stability refers, for example, to
substantially no or minimal change in solid area density,
especially in 60 percent halftone prints, and no or minimal random
color variability from print to print after a number of xerographic
prints, for example 50 kiloprints.
[0010] Also disclosed are methods of imaging and printing with the
photoconductor devices illustrated herein. These methods generally
involve the formation of an electrostatic latent image on the
imaging member, followed by developing the image with a toner
composition comprised, for example, of thermoplastic resin,
colorant, such as pigment, charge additive, and surface additive,
reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the
disclosures of which are totally incorporated herein by reference,
subsequently transferring the image to a suitable substrate, and
permanently affixing the image thereto. In those environments
wherein the device is to be used in a printing mode, the imaging
method involves the same operation with the exception that exposure
can be accomplished with a laser device or image bar. More
specifically, flexible belts disclosed herein can be selected for
the Xerox Corporation iGEN3.RTM. machines that generate with some
versions over 100 copies per minute. Processes of imaging,
especially xerographic imaging and printing, including digital,
and/or color printing, are thus encompassed by the present
disclosure. The imaging members are in embodiments sensitive in the
wavelength region of, for example, from about 400 to about 900
nanometers, and in particular from about 650 to about 850
nanometers, thus diode lasers can be selected as the light source.
Moreover, the imaging members of this disclosure are useful in high
resolution color xerographic applications, particularly high speed
color copying and printing processes.
REFERENCES
[0011] There is illustrated in U.S. Pat. No. 6,913,863, is a
photoconductive imaging member comprised of a hole blocking layer,
a photogenerating layer, and a charge transport layer, and wherein
the hole blocking layer is comprised of a metal oxide; and a
mixture of a phenolic compound and a phenolic resin wherein the
phenolic compound contains at least two phenolic groups.
[0012] Layered photoresponsive imaging members have been described
in numerous U.S. patents, such as U.S. Pat. No. 4,265,990, wherein
there is illustrated an imaging member comprised of a
photogenerating layer, and an aryl amine hole transport layer.
[0013] Further, in U.S. Pat. No. 4,555,463, there is illustrated a
layered imaging member with a chloroindium phthalocyanine
photogenerating layer. In U.S. Pat. No. 4,587,189, there is
illustrated a layered imaging member with, for example, a perylene,
pigment photogenerating component. Both of the aforementioned
patents disclose an aryl amine component, such as
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
dispersed in a polycarbonate binder as a hole transport layer. The
above components, such as the photogenerating compounds and the
aryl amine charge transport, can be selected for the imaging
members of the present disclosure in embodiments thereof.
[0014] Illustrated in U.S. Pat. No. 5,521,306, the disclosure of
which is totally incorporated herein by reference, is a process for
the preparation of Type V hydroxygallium phthalocyanine comprising
the in situ formation of an alkoxy-bridged gallium phthalocyanine
dimer, hydrolyzing the dimer to hydroxygallium phthalocyanine, and
subsequently converting the hydroxygallium phthalocyanine product
to Type V hydroxygallium phthalocyanine.
[0015] Illustrated in U.S. Pat. No. 5,482,811, the disclosure of
which is totally incorporated herein by reference, is a process for
the preparation of hydroxygallium phthalocyanine photogenerating
pigments which comprises hydrolyzing a gallium phthalocyanine
precursor pigment by dissolving the hydroxygallium phthalocyanine
in a strong acid, and then reprecipitating the resulting dissolved
pigment in basic aqueous media; removing any ionic species formed
by washing with water; concentrating the resulting aqueous slurry
comprised of water and hydroxygallium phthalocyanine to a wet cake;
removing water from said slurry by azeotropic distillation with an
organic solvent, and subjecting said resulting pigment slurry to
mixing with the addition of a second solvent to cause the formation
of said hydroxygallium phthalocyanine polymorphs.
[0016] Also, in U.S. Pat. No. 5,473,064, the disclosure of which is
totally incorporated herein by reference, there is illustrated a
process for the preparation of photogenerating pigments of
hydroxygallium phthalocyanine Type V essentially free of chlorine,
where a pigment precursor Type I chlorogallium phthalocyanine is
prepared by the reaction of gallium chloride in a solvent, such as
N-methylpyrrolidone, present in an amount of from about 10 to about
100 parts, with 1,3-diiminoisoindolene (DI.sup.3) in an amount of
from about 1 to about 10 parts, for each part of gallium chloride
that is reacted; hydrolyzing said pigment precursor chlorogallium
phthalocyanine Type I by standard methods, for example acid
pasting, whereby the pigment precursor is dissolved in concentrated
sulfuric acid and then reprecipitated in a solvent, such as water,
or a dilute ammonia solution, for example from about 10 to about 15
percent; and subsequently treating the resulting hydrolyzed pigment
hydroxygallium phthalocyanine Type I with a solvent, such as
N,N-dimethylformamide, present in an amount of from about 1 to
about 50 volume parts, for each weight part of pigment
hydroxygallium phthalocyanine that is used by, for example, ball
milling the Type I hydroxygallium phthalocyanine pigment in the
presence of spherical glass beads, approximately 1 to 5 millimeters
in diameter, at room temperature, about 25.degree. C., for a period
of from about 12 hours to about 1 week, and more specifically,
about 24 hours.
[0017] The appropriate components, and processes of the above
recited patents may be selected for the present disclosure in
embodiments thereof.
SUMMARY
[0018] Disclosed in embodiments are imaging members with many of
the advantages illustrated herein, such as extended lifetimes of
service of, for example, in excess of about 1,500,000 imaging
cycles; excellent electrical characteristics; stable electrical
properties; excellent image ghosting characteristics; excellent
lateral charge migration (LCM) resistance; excellent deletion
resistance; acceptable background and/or minimal charge deficient
spots (CDS); consistent V.sub.r (residual potential) that is
substantially flat or no change over a number of imaging cycles as
illustrated by the generation of known PIDC (Photoinduced Discharge
Curve), and the like. Also disclosed are layered photoresponsive
imaging members which are responsive to near infrared radiation of
from about 700 to about 900 nanometers.
[0019] Further disclosed are layered flexible photoresponsive
imaging members with sensitivity to visible light and with
mechanically robust charge transport layers.
[0020] Additionally disclosed are flexible imaging members with
optional hole blocking layers comprised of metal oxides, phenolic
resins, and optional phenolic compounds, and which phenolic
compounds contain at least two, and more specifically, two to ten
phenol groups or phenolic resins with, for example, a weight
average molecular weight ranging from about 500 to about 3,000
permitting, for example, a hole blocking layer with excellent
efficient electron transport which usually results in a desirable
photoconductor low residual potential V.sub.low.
Embodiments
[0021] Aspects of the present disclosure relate to an imaging
member comprising an optional supporting substrate, a
photogenerating layer, and at least one charge transport layer
comprised of at least one charge transport component, and where the
photogenerating layer comprises a fatty ester, especially a
vulcanized fatty ester; a photoconductor comprising a supporting
substrate, a vulcanized fatty ester containing photogenerating
layer, and at least one charge transport layer; a photoconductor
where the fatty ester is present in an amount of from about 0.1 to
about 30 weight percent, from about 1 to about 20 weight percent,
from 1 to about 10 weight percent, from 1 to about 5 weight
percent, from about 4 to about 6 weight percent, and yet more
specifically, about 5 weight percent, and wherein the
photogenerating layer is comprised of the fatty ester and a
photogenerating pigment, and at least one charge transport layer
comprised of a hole transport compound or compounds, and the at
least one charge transport layer is 1, 2, or 3 layers; a
photoconductor comprising a supporting substrate, a photogenerating
layer, and at least one charge transport layer, and wherein the
photogenerating layer includes therein a vulcanized fatty ester; a
photoconductor comprising a supporting substrate, a vulcanized
fatty ester containing photogenerating layer, and a charge
transport layer, and wherein the photogenerating layer comprises a
photogenerating component and the fatty ester; and a photoconductor
comprising a photogenerating layer, and at least one charge
transport layer, and wherein the photogenerating layer is comprised
of at least one photogenerating pigment and a fatty ester, and
wherein the fatty ester is present in an amount of from about 1 to
about 12 weight percent, and the at least one charge transport
layer is 1, 2, or 3 layers.
[0022] Various effective amounts of the fatty ester, and more
specifically, the vulcanized fatty ester can be added to the
photogenerating layer components such as, for example, from about
0.1 to about 30 weight percent, from about 1 to about 20 weight
percent, from about 0.5 to about 30, from about 1 to about 20, from
about 1 to about 10, or from about 1 to about 5 weight percent, and
wherein the photogenerating layer and at least one charge transport
layer include a resin binder, and wherein the at least one charge
transport layer is from 2 to about 5 layers, and the
photogenerating layer is situated between the substrate and the at
least one charge transport layer; and a drum, or flexible
xerographic imaging photoconductive member comprising a supporting
substrate, a vulcanized fatty ester photogenerating layer, and at
least two charge transport layers.
[0023] In embodiments thereof, there is disclosed a vulcanized
fatty ester photoconductive imaging member comprised of a
supporting substrate, a photogenerating layer thereover, a charge
transport layer, and an overcoat charge transport layer; a
photoconductive member with a photogenerating layer of a thickness
of from about 0.1 to about 10 microns, at least one transport layer
each of a thickness of from about 5 to about 100 microns; a
xerographic imaging apparatus containing a charging component, a
development component, a transfer component, and a fixing
component, and wherein the apparatus contains a photoconductive
imaging member comprised of a supporting substrate, and thereover a
layer comprised of a photogenerating pigment and a fatty ester, and
a charge transport layer or layers, and thereover an overcoat
charge transport layer, and where the transport layer is of a
thickness of from about 10 to about 75 microns; a member wherein
the vulcanized fatty ester or mixtures thereof is present in an
amount of from about 1 to about 20 weight percent, or from about 5
to about 10 weight percent; a member wherein the photogenerating
layer contains a photogenerating pigment present in an amount of
from about 10 to about 95 weight percent; a member wherein the
thickness of the photogenerating layer is from about 0.2 to about 4
microns; a member wherein the photogenerating layer contains an
inactive polymer binder; a member wherein the binder is present in
an amount of from about 20 to about 90 percent by weight, and
wherein the total of all layer components is about 100 percent; a
member wherein the photogenerating component is a hydroxygallium
phthalocyanine or a titanyl phthalocyanine that absorbs light of a
wavelength of from about 370 to about 950 nanometers; an imaging
member wherein the supporting substrate is comprised of a
conductive substrate comprised of a metal; an imaging member
wherein the conductive substrate is aluminum, aluminized
polyethylene terephthalate, or titanized polyethylene
terephthalate; an imaging member wherein the photogenerating
resinous binder is selected from the group consisting of known
suitable polymers like polyesters, polyvinyl butyrals,
polycarbonates, polystyrene-b-polyvinyl pyridine, and polyvinyl
formals; an imaging member wherein the photogenerating pigment is a
metal free phthalocyanine; a photoconductor wherein each of the
charge transport layers, especially a first and second layer,
comprises
##STR00001##
wherein X is selected from the group consisting of at least one of
alkyl, alkoxy, and halogen such as methyl and chloride; and in
embodiments where there is a total of four X substituents on each
of the four terminating rings; an imaging member wherein alkyl and
alkoxy contain from about 1 to about 15 carbon atoms; an imaging
member wherein alkyl contains from about 1 to about 5 carbon atoms;
an imaging member wherein alkyl is methyl; an imaging member
wherein each of or at least one of the charge transport layers,
especially a first and second charge transport layer, comprises
##STR00002##
wherein X, Y and Z are independently selected from the group
comprised of at least one of alkyl, alkoxy, aryl, and halogen, and
in embodiments Z can be present, Y can be present, or both Y and Z
are present; or wherein the charge transport component is
##STR00003##
wherein X and Y are independently alkyl, alkoxy, aryl, a halogen,
or mixtures thereof, an imaging member, and wherein, for example,
alkyl and alkoxy contains from about 1 to about 15 carbon atoms;
alkyl contains from about 1 to about 5 carbon atoms; and wherein
the resinous binder is selected from the group consisting of
polycarbonates, polyarylates, and polystyrene; a photoconductor for
use in xerographic imaging and printing systems, such as the Xerox
Corporation iGen3.RTM. machines, wherein the photogenerating
pigment present in the photogenerating layer is comprised of
chlorogallium phthalocyanine, titanyl phthalocyanine, or Type V
hydroxygallium phthalocyanine prepared by hydrolyzing a gallium
phthalocyanine precursor by dissolving the hydroxygallium
phthalocyanine in a strong acid, and then reprecipitating the
resulting dissolved precursor in a basic aqueous media; removing
the ionic species formed by washing with water; concentrating the
resulting aqueous slurry comprised of water and hydroxygallium
phthalocyanine to a wet cake; removing water from the wet cake by
drying; and subjecting the resulting dry pigment to mixing with the
addition of a second solvent to cause the formation of the
hydroxygallium phthalocyanine; an imaging member wherein the Type V
hydroxygallium phthalocyanine has major peaks, as measured with an
X-ray diffractometer, at Bragg angles (2 theta.+-.0.2.degree.) 7.4,
9.8, 12.4, 16.2, 17.6, 18.4, 21.9, 23.9, 25.0, 28.1 degrees, and
the highest peak at 7.4 degrees; a method of imaging wherein the
imaging member is exposed to light of a wavelength of from about
400 to about 950 nanometers; a member wherein the photogenerating
layer is situated between the substrate and the charge transport
layer; a member wherein the charge transport layer is situated
between the substrate and the photogenerating layer, and wherein
the number of charge transport layers is two; a member wherein the
photogenerating layer is of a thickness of from about 0.1 to about
25 microns; a member wherein the photogenerating component amount
is from about 0.05 to about 20 weight percent, and wherein the
photogenerating pigment is dispersed in from about 10 to about 80
weight percent of a polymer binder; a member wherein the thickness
of the photogenerating layer is from about 0.1 to about 11 microns;
a member wherein the photogenerating and charge transport layer
components are contained in a polymer binder, and wherein the
binder is present in an amount of from about 50 to about 90 percent
by weight, and wherein the total of the layer components is about
100 percent; a photoconductor wherein the photogenerating resinous
binder is selected from the group consisting of at least one of
polyesters, polyvinyl butyrals, polycarbonates,
polystyrene-b-polyvinyl pyridine, and polyvinyl formals; an imaging
member wherein the photogenerating component is Type V
hydroxygallium phthalocyanine, titanyl phthalocyanine,
chlorogallium phthalocyanine, or mixtures thereof, and the charge
transport layer contains a hole transport of
N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-p-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-m-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-o-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4''--
diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2-ethyl-6-methylphenyl)-[p-terp-
henyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4''-
-diamine,
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[p-terphenyl]-4,4''-diami-
ne molecules, and wherein the hole transport resinous binder is
selected from the group consisting of polycarbonates and
polystyrene; an imaging member wherein the photogenerating layer
contains a metal free phthalocyanine; an imaging member wherein the
photogenerating layer contains an alkoxygallium phthalocyanine; a
photoconductive imaging member with a blocking layer contained as a
coating on a substrate, and an adhesive layer coated on the
blocking layer; an imaging member further containing an adhesive
layer and a hole blocking layer; a color method of imaging which
comprises generating an electrostatic latent image on the imaging
member, developing the latent image, transferring, and fixing the
developed electrostatic image to a suitable substrate;
photoconductive imaging members comprised of a supporting
substrate, a photogenerating layer, a hole transport layer, and a
top overcoating layer in contact with the hole transport layer or,
in embodiments, in contact with the photogenerating layer, and in
embodiments wherein a plurality of charge transport layers are
selected, such as for example, from 2 to about 10, and more
specifically, 2 may be selected; and a photoconductive imaging
member comprised of an optional supporting substrate, a
photogenerating layer, and a first, second, and third charge
transport layer.
[0024] Examples of the vulcanized fatty esters, incorporated into
the photogenerating photoconductors disclosed herein, and available
from RheinChemie, such as ADDITIN.RTM. RC8000, can be prepared from
vulcanization (sulfurization) of unsaturated fatty esters. Sulfur
sources that may be used in the sulfurization reaction include
elemental sulfur, sulfur monochloride, sulfur dichloride, sodium
sulfide, sodium polysulfide, and mixtures of these added together
or at different stages of the sulfurization process. Examples of
unsaturated fatty esters that can be selected for the vulcanization
reaction are, for example, corn oil, canola oil, cottonseed oil,
grapeseed oil, olive oil, palm oil, peanut oil, coconut oil,
rapeseed oil, safflower seed oil, sesame seed oil, soybean oil,
sunflower seed oil, tallow, and mixtures thereof. A typical
reaction mechanism is as follows
##STR00004##
[0025] Typically, from about 60 to about 95 parts of a fatty ester
is mixed with from about 40 to about 5 parts of sulfur (S.sub.x,
where x=8), and heated to about 120.degree. C. to about 200.degree.
C., or 170.degree. C., for about 5 to about 120 minutes, or more
specifically, about 30 minutes. The resulting vulcanized fatty
esters possess a sulfur content of, for example, from about 5 to
about 40 weight percent, from about 10 to about 30 weight percent,
from about 10 to about 20 weight percent, and the like.
[0026] Generally, the fatty esters selected for the photogenerating
layer possess unsaturation in the aliphatic chains, and where these
reactive chains are reacted with, for example, sulfur, and where
the resulting vulcanized fatty ester containing photogenerating
layer enables a number of the advantages illustrated herein, and
for example, substantial adhesion of the photogenerating layer to
the substrate and the charge transport layers, and where when
tested no peeling of the photoconductor layers was observed.
[0027] Specific examples of vulcanized fatty esters that may be
selected for inclusion in the photogenerating layer are sulfurized
corn oil, sulfurized canola oil, sulfurized cottonseed oil,
sulfurized grapeseed oil, sulfurized olive oil, sulfurized palm
oil, sulfurized peanut oil, sulfurized coconut oil, sulfurized
rapeseed oil, sulfurized sesame seed oil, sulfurized soybean oil,
sulfurized sunflower seed oil, sulfurized tallow, sulfurized fish
oil including herring oil and sardine oil. Commercial vulcanized
fatty ester examples that may be selected for inclusion in the
photogenerating layer are ADDITIN.RTM. RC8000 which contains
approximately 20 weight percent sulfur content, ADDITIN.RTM. R4410
which contains approximately 9.5 weight percent sulfur content,
ADDITIN.RTM. R4412-F which contains approximately 12.5 weight
percent sulfur content, ADDITIN.RTM. R4417 which contains
approximately 17.5 weight percent sulfur content, ADDITIN.RTM.
RC2515 which contains approximately 15 weight percent sulfur
content, ADDITIN.RTM. RC2526 which contains approximately 26 weight
percent sulfur content, ADDITIN.RTM. RC2810-A which contains
approximately 10 weight percent sulfur content, ADDITIN.RTM.
RC2814-A which contains approximately 14 weight percent sulfur
content, and ADDITIN.RTM. RC2818-A which contains approximately 16
weight percent sulfur content, all from RheinChemie
Corporation.
PHOTOCONDUCTOR LAYER EXAMPLES
[0028] There can be selected for the photoconductors disclosed
herein a number of known layers, such as substrates,
photogenerating layers, charge transport layers (CTL), hole
blocking layers, adhesive layers, protective overcoat layers, and
the like. Examples, thicknesses, specific components of many of
these layers include the following.
[0029] The thickness of the substrate layer depends on many
factors, including economical considerations, electrical
characteristics, and the like, thus this layer may be of a
substantial thickness, for example over 3,000 microns, such as from
about 1,000 to about 3,500 microns, from about 1,000 to about 2,000
microns, from about 300 to about 700 microns, or of a minimum
thickness of, for example, about 100 to about 500 microns. In
embodiments, the thickness of this layer is from about 75 to about
300 microns, or from about 100 to about 150 microns.
[0030] The substrate may be opaque or substantially transparent,
and may comprise any suitable material. Accordingly, the substrate
may comprise a layer of an electrically nonconductive or conductive
material, such as an inorganic or an organic composition. As
electrically nonconducting materials, there may be employed various
resins known for this purpose including polyesters, polycarbonates,
polyamides, polyurethanes, and the like, which are flexible as thin
webs. An electrically conducting substrate may be any suitable
metal of, for example, aluminum, nickel, steel, copper, and the
like, or a polymeric material, as described above, filled with an
electrically conducting substance, such as carbon, metallic powder,
and the like, or an organic electrically conducting material. The
electrically insulating or conductive substrate may be in the form
of an endless flexible belt, a web, a rigid cylinder, a sheet, and
the like. The thickness of the substrate layer depends on numerous
factors, including strength desired and economical considerations.
For a drum, this layer may be of a substantial thickness of, for
example, up to many centimeters, or of a minimum thickness of less
than a millimeter. Similarly, a flexible belt may be of a
substantial thickness of, for example, about 250 microns, or of a
minimum thickness of less than about 50 microns, provided there are
no adverse effects on the final electrophotographic device. In
embodiments where the substrate layer is not conductive, the
surface thereof may be rendered electrically conductive by an
electrically conductive coating. The conductive coating may vary in
thickness over substantially wide ranges depending upon the optical
transparency, degree of flexibility desired, and economic
factors.
[0031] Illustrative examples of substrates are as illustrated
herein, and more specifically, layers selected for the imaging
members of the present disclosure, and which substrates can be
opaque or substantially transparent comprise a layer of insulating
material including inorganic or organic polymeric materials, such
as MYLAR.RTM. a commercially available polymer, MYLAR.RTM.
containing titanium, a layer of an organic or inorganic material
having a semiconductive surface layer, such as indium tin oxide or
aluminum arranged thereon, or a conductive material inclusive of
aluminum, chromium, nickel, brass, or the like. The substrate may
be flexible, seamless, or rigid, and may have a number of many
different configurations, such as for example, a plate, a
cylindrical drum, a scroll, an endless flexible belt, and the like.
In embodiments, the substrate is in the form of a seamless flexible
belt. In some situations, it may be desirable to coat on the back
of the substrate, particularly when the substrate is a flexible
organic polymeric material, an anticurl layer, such as for example
polycarbonate materials commercially available as
MAKROLON.RTM..
[0032] The photogenerating layer, in embodiments, is comprised of a
number of known photogenerating pigments, such as for example,
about 50 weight percent of Type V hydroxygallium phthalocyanine,
titanyl phthalocyanine or chlorogallium phthalocyanine, and about
50 weight percent of a resin binder like poly(vinyl
chloride-co-vinyl acetate) copolymer, such as VMCH (available from
Dow Chemical), or polycarbonate. Generally, the photogenerating
layer can contain known photogenerating pigments, such as metal
phthalocyanines, metal free phthalocyanines, alkylhydroxyl gallium
phthalocyanines, hydroxygallium phthalocyanines, chlorogallium
phthalocyanines, perylenes, especially bis(benzimidazo)perylene,
titanyl phthalocyanines, and the like, and more specifically,
vanadyl phthalocyanines, Type V hydroxygallium phthalocyanines, and
inorganic components, such as selenium, selenium alloys, and
trigonal selenium. The photogenerating pigment can be dispersed in
a resin binder similar to the resin binders selected for the charge
transport layer, or alternatively no resin binder need be present.
Generally, the thickness of the photogenerating layer depends on a
number of factors, including the thicknesses of the other layers,
and the amount of photogenerating material contained in the
photogenerating layer. Accordingly, this layer can be of a
thickness of, for example, from about 0.05 to about 10 microns, and
more specifically, from about 0.25 to about 2 microns when, for
example, the photogenerating compositions are present in an amount
of from about 30 to about 75 percent by volume. The maximum
thickness of this layer in embodiments is dependent primarily upon
factors, such as photosensitivity, electrical properties, and
mechanical considerations. The photogenerating layer binder resin
is present in various suitable amounts, for example from about 1 to
about 50 weight percent, and more specifically, from about 1 to
about 10 weight percent, and which resin may be selected from a
number of known polymers, such as poly(vinyl butyral), poly(vinyl
carbazole), polyesters, polycarbonates, polyarylates, poly(vinyl
chloride), polyacrylates and methacrylates, copolymers of vinyl
chloride and vinyl acetate, phenolic resins, polyurethanes,
poly(vinyl alcohol), polyacrylonitrile, polystyrene, other known
suitable binders, and the like. It is desirable to select a coating
solvent that does not substantially disturb or adversely affect the
previously coated layers of the device. Examples of coating
solvents for the photogenerating layer are ketones, alcohols,
aromatic hydrocarbons, halogenated aliphatic hydrocarbons,
silanols, amines, amides, esters, and the like. Specific solvent
examples are cyclohexanone, acetone, methyl ethyl ketone, methanol,
ethanol, butanol, amyl alcohol, toluene, xylene, chlorobenzene,
carbon tetrachloride, chloroform, methylene chloride,
trichloroethylene, dichloroethane, tetrahydrofuran, dioxane,
diethyl ether, dimethyl formamide, dimethyl acetamide, butyl
acetate, ethyl acetate, methoxyethyl acetate, and the like.
[0033] The photogenerating layer may comprise amorphous films of
selenium and alloys of selenium and arsenic, tellurium, germanium,
and the like; hydrogenated amorphous silicon; and compounds of
silicon and germanium, carbon, oxygen, nitrogen, and the like
fabricated by vacuum evaporation or deposition. The photogenerating
layers may also comprise inorganic pigments of crystalline selenium
and its alloys; Groups II to VI compounds; and organic pigments,
such as quinacridones, polycyclic pigments, such as dibromo
anthanthrone pigments, perylene and perinone diamines, polynuclear
aromatic quinones, azo pigments including bis-, tris- and
tetrakis-azos; and the like dispersed in a film forming polymeric
binder, and fabricated by solvent coating techniques.
[0034] Infrared sensitivity can be desired for photoreceptors
exposed to low cost semiconductor laser diode light exposure
devices where, for example, the absorption spectrum and
photosensitivity of the phthalocyanines selected depend on the
central metal atom thereof. Examples of these phthalocyanines
selected for the photogenerating layer of the photoconductors of
the present disclosure include oxyvanadium phthalocyanine,
chloroaluminum phthalocyanine, copper phthalocyanine, oxytitanium
phthalocyanine, chlorogallium phthalocyanine, hydroxygallium
phthalocyanine, magnesium phthalocyanine, and metal free
phthalocyanine. The phthalocyanines exist in many crystal forms,
and have a strong influence on photogeneration.
[0035] A number of titanyl phthalocyanines, or oxytitanium
phthalocyanines photogenerating pigments or components can be
selected for the photoconductors illustrated herein inclusive of
photogenerating pigments known to absorb near infrared light at,
for example, about 800 nanometers, and which exhibit improved
sensitivity compared to other pigments, such as, for example,
hydroxygallium phthalocyanine. Generally, titanyl phthalocyanine is
known to have five main crystal forms known as Types I, II, III, X,
and IV. For example, U.S. Pat. Nos. 5,189,155 and 5,189,156, the
disclosures of which are totally incorporated herein by reference,
disclose a number of methods for obtaining various polymorphs of
titanyl phthalocyanine. Additionally, U.S. Pat. Nos. 5,189,155 and
5,189,156 are directed to processes for obtaining Types I, X, and
IV phthalocyanines. U.S. Pat. No. 5,153,094, the disclosure of
which is totally incorporated herein by reference, relates to the
preparation of titanyl phthalocyanine polymorphs including Types I,
II, III, and IV polymorphs. U.S. Pat. No. 5,166,339, the disclosure
of which is totally incorporated herein by reference, discloses
processes for preparing Types I, IV, and X titanyl phthalocyanine
polymorphs, as well as the preparation of two polymorphs designated
as Type Z-1 and Type Z-2.
[0036] To obtain a titanyl phthalocyanine pigment based
photoconductor with high sensitivity to near infrared light, it is
believed of value to control not only the purity and chemical
structure of the pigment, as is generally the situation with
organic photoconductors, but also to prepare the pigment in a
certain crystal modification. Consequently, it is desirable to
provide a photoconductor where the titanyl phthalocyanine is
generated by a process that will provide high sensitivity titanyl
phthalocyanines.
[0037] In embodiments, the Type V phthalocyanine pigment included
in the photogenerating layer can be generated by dissolving Type I
titanyl phthalocyanine in a solution comprising a trihaloacetic
acid and an alkylene halide; adding the resulting mixture
comprising the dissolved Type I titanyl phthalocyanine to a
solution comprising an alcohol and an alkylene halide thereby
precipitating a Type Y titanyl phthalocyanine; and treating the
resulting Type Y titanyl phthalocyanine with monochlorobenzene.
[0038] With further respect to the titanyl phthalocyanines selected
for the photogenerating layer, such phthalocyanines can exhibit a
crystal phase that is distinguishable from other known titanyl
phthalocyanine polymorphs, and are designated as Type V polymorphs
prepared by converting a Type I titanyl phthalocyanine to a Type V
titanyl phthalocyanine pigment. The processes include converting a
Type I titanyl phthalocyanine to an intermediate titanyl
phthalocyanine, which is designated as a Type Y titanyl
phthalocyanine, and then subsequently converting the Type Y titanyl
phthalocyanine to a Type V titanyl phthalocyanine.
[0039] In one embodiment, the titanyl phthalocyanine process
comprises (a) dissolving a Type I titanyl phthalocyanine in a
suitable solvent; (b) adding the solvent solution comprising the
dissolved Type I titanyl phthalocyanine to a quenching solvent
system to precipitate an intermediate titanyl phthalocyanine
(designated as a Type Y titanyl phthalocyanine); and (c) treating
the resultant Type Y phthalocyanine with a halo, such as, for
example, monochlorobenzene, to obtain a resultant high sensitivity
titanyl phthalocyanine, which is designated herein as a Type V
titanyl phthalocyanine. In another embodiment, prior to treating
the Type Y phthalocyanine with a halo, such as monochlorobenzene,
the Type Y titanyl phthalocyanine may be washed with various
solvents including, for example, water, and/or methanol. The
quenching solvents system to which the solution comprising the
dissolved Type I titanyl phthalocyanine is added comprises, for
example, an alkyl alcohol and an alkylene halide.
[0040] The titanyl phthalocyanine process further provides a
titanyl phthalocyanine having a crystal phase distinguishable from
other known titanyl phthalocyanines. The titanyl phthalocyanine
Type V prepared by a process illustrated herein is distinguishable
from, for example, Type IV titanyl phthalocyanines in that a Type V
titanyl phthalocyanine exhibits an X-ray powder diffraction
spectrum having four characteristic peaks at 9.0.degree.,
9.6.degree., 24.0.degree., and 27.2.degree., while Type IV titanyl
phthalocyanines typically exhibit only three characteristic peaks
at 9.6.degree., 24.0.degree., and 27.2.degree..
[0041] In a process embodiment for preparing a high sensitivity
phthalocyanine, a Type I titanyl phthalocyanine is dissolved in a
suitable solvent. In embodiments, a Type I titanyl phthalocyanine
is dissolved in a solvent comprising a trihaloacetic acid and an
alkylene halide. The alkylene halide comprises, in embodiments,
from about one to about six carbon atoms. An example of a suitable
trihaloacetic acid includes, but is not limited to, trifluoroacetic
acid. In one embodiment, the solvent for dissolving a Type I
titanyl phthalocyanine comprises trifluoroacetic acid and methylene
chloride. In embodiments, the trihaloacetic acid is present in an
amount of from about one to about 100 volume parts of the solvent,
and the alkylene halide is present in an amount of from about one
to about 100 volume parts of the solvent. In one embodiment, the
solvent comprises methylene chloride and trifluoroacetic acid in a
volume-to-volume ratio of about 4 to 1. The Type I titanyl
phthalocyanine is dissolved in the solvent by stirring for an
effective period of time, such as, for example, for about 30
seconds to about 24 hours, at room temperature. The Type I titanyl
phthalocyanine is dissolved by, for example, stirring in the
solvent for about one hour at room temperature (about 25.degree.
C.). The Type I titanyl phthalocyanine may be dissolved in the
solvent in either air, or in an inert atmosphere (argon or
nitrogen).
[0042] Examples of binders for the photogenerating layer are
thermoplastic and thermosetting resins, such as polycarbonates,
polyesters, polyamides, polyurethanes, polystyrenes,
polyarylsilanols, polyarylsulfones, polybutadienes, polysulfones,
polysilanolsulfones, polyethylenes, polypropylenes, polyimides,
polymethylpentenes, poly(phenylene sulfides), poly(vinyl acetate),
polysiloxanes, polyacrylates, polyvinyl acetals, polyamides,
polyimides, amino resins, phenylene oxide resins, terephthalic acid
resins, phenoxy resins, epoxy resins, phenolic resins, polystyrene
and acrylonitrile copolymers, poly(vinyl chloride), vinyl chloride
and vinyl acetate copolymers, acrylate copolymers, alkyd resins,
cellulosic film formers, poly(amideimide), styrene butadiene
copolymers, vinylidene chloride-vinyl chloride copolymers, vinyl
acetate-vinylidene chloride copolymers, styrene-alkyd resins,
poly(vinyl carbazole), and the like. These polymers may be block,
random, or alternating copolymers.
[0043] The photogenerating composition or pigment is present in the
resinous binder composition in various amounts. Generally, however,
from about 5 to about 90 percent by weight of the photogenerating
pigment is dispersed in about 10 to about 95 percent by weight of
the resinous binder, or from about 20 to about 50 percent by weight
of the photogenerating pigment is dispersed in about 80 to about 50
percent by weight of the resinous binder composition. In one
embodiment, about 50 percent by weight of the photogenerating
pigment is dispersed in about 50 percent by weight of the resinous
binder composition.
[0044] Various suitable and conventional known processes may be
used to mix, and thereafter apply the photogenerating layer coating
mixture like spraying, dip coating, roll coating, wire wound rod
coating, vacuum sublimation, and the like. For some applications,
the photogenerating layer may be fabricated in a dot or line
pattern. Removal of the solvent of a solvent-coated photogenerating
layer may be effected by any known conventional techniques such as
oven drying, infrared radiation drying, air drying, and the
like.
[0045] The coating of the photogenerating layer in embodiments of
the present disclosure can be accomplished to achieve a final dry
thickness of the photogenerating layer as illustrated herein, and
for example, from about 0.01 to about 30 microns after being dried
at, for example, about 40.degree. C. to about 150.degree. C. for
about 1 to about 90 minutes. More specifically, a photogenerating
layer of a thickness, for example, of from about 0.1 to about 30
microns, or from about 0.5 to about 2 microns can be applied to or
deposited on the substrate, on other surfaces in between the
substrate and the charge transport layer, and the like. A charge
blocking layer or hole blocking layer may optionally be applied to
the electrically conductive surface prior to the application of a
photogenerating layer. When desired, an adhesive layer may be
included between the charge blocking, hole blocking layer, or
interfacial layer, and the photogenerating layer. Usually, the
photogenerating layer is applied onto the blocking layer, and a
charge transport layer or plurality of charge transport layers are
formed on the photogenerating layer. The photogenerating layer may
be applied on top of or below the charge transport layer.
[0046] In embodiments, a suitable known adhesive layer can be
included in the photoconductor. Typical adhesive layer materials
include, for example, polyesters, polyurethanes, and the like. The
adhesive layer thickness can vary, and in embodiments is, for
example, from about 0.05 to about 0.3 micron. The adhesive layer
can be deposited on the hole blocking layer by spraying, dip
coating, roll coating, wire wound rod coating, gravure coating,
Bird applicator coating, and the like. Drying of the deposited
coating may be effected by, for example, oven drying, infrared
radiation drying, air drying, and the like.
[0047] As an optional adhesive layer or layers usually in contact
with or situated between the hole blocking layer and the
photogenerating layer, there can be selected various known
substances inclusive of copolyesters, polyamides, poly(vinyl
butyral), poly(vinyl alcohol), polyurethane, and polyacrylonitrile.
This layer is, for example, of a thickness of from about 0.001 to
about 1 micron, or from about 0.1 to about 0.5 micron. Optionally,
this layer may contain effective suitable amounts, for example from
about 1 to about 10 weight percent, of conductive and nonconductive
particles, such as zinc oxide, titanium dioxide, silicon nitride,
carbon black, and the like, to provide, for example, in embodiments
of the present disclosure further desirable electrical and optical
properties.
[0048] The optional hole blocking or undercoat layer for the
imaging members of the present disclosure can contain a number of
components including known hole blocking components, such as amino
silanes, doped metal oxides, a metal oxide like titanium, chromium,
zinc, tin, and the like; a mixture of phenolic compounds and a
phenolic resin, or a mixture of two phenolic resins, and optionally
a dopant such as SiO.sub.2. The phenolic compounds usually contain
at least two phenol groups, such as bisphenol A
(4,4'-isopropylidenediphenol), E (4,4'-ethylidenebisphenol), F
(bis(4-hydroxyphenyl)methane), M
(4,4'-(1,3-phenylenediisopropylidene)bisphenol), P
(4,4'-(1,4-phenylene diisopropylidene)bisphenol), S
(4,4'-sulfonyldiphenol), and Z (4,4'-cyclohexylidenebisphenol);
hexafluorobisphenol A (4,4'-(hexafluoro isopropylidene) diphenol),
resorcinol, hydroxyquinone, catechin, and the like.
[0049] The hole blocking layer can be, for example, comprised of
from about 20 to about 80 weight percent, and more specifically,
from about 55 to about 65 weight percent of a suitable component
like a metal oxide, such as TiO.sub.2; from about 20 to about 70
weight percent, and more specifically, from about 25 to about 50
weight percent of a phenolic resin; from about 2 to about 20 weight
percent, and more specifically, from about 5 to about 15 weight
percent of a phenolic compound containing, for example, at least
two phenolic groups, such as bisphenol S; and from about 2 to about
15 weight percent, and more specifically, from about 4 to about 10
weight percent of a plywood suppression dopant, such as SiO.sub.2.
The hole blocking layer coating dispersion can, for example, be
prepared as follows. The metal oxide/phenolic resin dispersion is
first prepared by ball milling or dynomilling until the median
particle size of the metal oxide in the dispersion is less than
about 10 nanometers, for example from about 5 to about 9
nanometers. To the above dispersion are added a phenolic compound
and dopant followed by mixing. The hole blocking layer coating
dispersion can be applied by dip coating or web coating, and the
layer can be thermally cured after coating. The hole blocking layer
resulting is, for example, of a thickness of from about 0.01 to
about 30 microns, and more specifically, from about 0.1 to about 8
microns. Examples of phenolic resins include formaldehyde polymers
with phenol, p-tert-butylphenol, cresol, such as VARCUM.RTM. 29159
and 29101 (available from OxyChem Company), and DURITE.RTM. 97
(available from Borden Chemical); formaldehyde polymers with
ammonia, cresol and phenol, such as VARCUM.RTM. 29112 (available
from OxyChem Company); formaldehyde polymers with
4,4'-(1-methylethylidene)bisphenol, such as VARCUM.RTM. 29108 and
29116 (available from OxyChem Company); formaldehyde polymers with
cresol and phenol, such as VARCUM.RTM. 29457 (available from
OxyChem Company), DURITE.RTM. SD-423A, SD-422A (available from
Borden Chemical); or formaldehyde polymers with phenol and
p-tert-butylphenol, such as DURITE.RTM. ESD 556C (available from
Borden Chemical).
[0050] Charge transport layer components and molecules include a
number of known materials as illustrated herein, such as aryl
amines, which layer is generally of a thickness of from about 5 to
about 75 microns, and more specifically, of a thickness of from
about 10 to about 40 microns. Examples of charge transport layer
components include
##STR00005##
wherein X is alkyl, alkoxy, aryl, a halogen, or mixtures thereof,
and especially those substituents selected from the group
consisting of Cl and CH.sub.3; and molecules of the following
formula
##STR00006##
wherein X and Y are independently alkyl, alkoxy, aryl, a halogen,
or mixtures thereof.
[0051] Alkyl and alkoxy contain, for example, from 1 to about 25
carbon atoms, and more specifically, from 1 to about 12 carbon
atoms, such as methyl, ethyl, propyl, butyl, pentyl, and the
corresponding alkoxides. Aryl can contain from 6 to about 36 carbon
atoms, such as phenyl, and the like. Halogen includes chloride,
bromide, iodide and fluoride. Substituted alkyls, alkoxys, and
aryls can also be selected in embodiments.
[0052] Examples of specific aryl amines include
N,N'-diphenyl-N,N'-bis(alkylphenyl)-1,1-biphenyl-4,4'-diamine
wherein alkyl is selected from the group consisting of methyl,
ethyl, propyl, butyl, hexyl, and the like;
N,N'-diphenyl-N,N'-bis(halophenyl)-1,1'-biphenyl-4,4'-diamine
wherein the halo substituent is a chloro substituent;
N,N'-bis(4-butylphenyl)-N,N'-di-p-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-m-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-o-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4''--
diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2-ethyl-6-methylphenyl)-[p-terp-
henyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4'--
diamine,
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[p-terphenyl]-4,4''-diamin-
e, and the like. Other known charge transport layer molecules can
be selected, reference for example, U.S. Pat. Nos. 4,921,773 and
4,464,450, the disclosures of which are totally incorporated herein
by reference.
[0053] Examples of polymer binder materials for the charge
transport layer or layers include polycarbonates, polyarylates,
acrylate polymers, vinyl polymers, cellulose polymers, polyesters,
polysiloxanes, polyamides, polyurethanes, poly(cyclo olefins),
epoxies, and random or alternating copolymers thereof; and more
specifically, polycarbonates such as
poly(4,4'-isopropylidene-diphenylene)carbonate (also referred to as
bisphenol-A-polycarbonate),
poly(4,4'-cyclohexylidinediphenylene)carbonate (also referred to as
bisphenol-Z-polycarbonate),
poly(4,4'-isopropylidene-3,3'-dimethyl-diphenyl)carbonate (also
referred to as bisphenol-C-polycarbonate), and the like. In
embodiments, the charge transport layer binders are comprised of
polycarbonate resins with a weight average molecular weight of from
about 20,000 to about 100,000, or with a molecular weight M.sub.w
of from about 50,000 to about 100,000 preferred. Generally, in
embodiments the transport layer contains from about 10 to about 75
percent by weight of the charge transport material, and more
specifically, from about 35 to about 50 percent of this
material.
[0054] The charge transport layer or layers, and more specifically,
a first charge transport in contact with the photogenerating layer,
and thereover a top or second charge transport overcoating layer
may comprise charge transporting small molecules dissolved or
molecularly dispersed in a film forming electrically inert polymer
such as a polycarbonate. In embodiments, "dissolved" refers, for
example, to forming a solution in which the small molecule and
silanol are dissolved in the polymer to form a homogeneous phase;
and "molecularly dispersed in embodiments"refers, for example, to
charge transporting molecules dispersed in the polymer, the small
molecules being dispersed in the polymer on a molecular scale.
Various charge transporting or electrically active small molecules
may be selected for the charge transport layer or layers. In
embodiments, charge transport refers, for example, to charge
transporting molecules as a monomer that allows the free charge
generated in the photogenerating layer to be transported across the
transport layer.
[0055] Examples of hole transporting molecules, especially for the
first and second charge transport layers, and present, for example,
in an amount of from about 45 to about 80 weight percent, include,
for example, pyrazolines such as 1-phenyl-3-(4'-diethylamino
styryl)-5-(4''-diethylamino phenyl)pyrazoline; aryl amines such as
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-p-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-m-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-o-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4''--
diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2-ethyl-6-methylphenyl)-[p-terp-
henyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4''-
-diamine,
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[p-terphenyl]-4,4''-diami-
ne; hydrazones such as N-phenyl-N-methyl-3-(9-ethyl)carbazyl
hydrazone, and 4-diethyl amino benzaldehyde-1,2-diphenyl hydrazone;
and vulcanized fatty esters, such as
2,5-bis(4-N,N'-diethylaminophenyl)-1,2,4-vulcanized fatty ester,
stilbenes, and the like. However, in embodiments, to minimize or
avoid cycle-up in equipment, such as printers, with high
throughput, the charge transport layer should be substantially free
(less than about two percent) of di or triamino-triphenyl methane.
A small molecule charge transporting compound that permits
injection of holes into the photogenerating layer with high
efficiency, and transports them across the charge transport layer
with short transit times, and which layer contains a binder and a
silanol includes
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-p-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-m-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-di-o-tolyl-[p-terphenyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4''--
diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2-ethyl-6-methylphenyl)-[p-terp-
henyl]-4,4''-diamine,
N,N'-bis(4-butylphenyl)-N,N'-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4''-
-diamine, and
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[p-terphenyl]-4,4''-diamine,
or mixtures thereof. If desired, the charge transport material in
the charge transport layer may comprise a polymeric charge
transport material, or a combination of a small molecule charge
transport material and a polymeric charge transport material.
[0056] The thickness of each of the charge transport layers in
embodiments is from about 5 to about 75 microns, but thicknesses
outside this range may, in embodiments, also be selected. The
charge transport layer should be an insulator to the extent that an
electrostatic charge placed on the hole transport layer is not
conducted in the absence of illumination at a rate sufficient to
prevent formation and retention of an electrostatic latent image
thereon. In general, the ratio of the thickness of the charge
transport layer to the photogenerating layer can be from about 2:1
to 200:1, and in some instances 400:1. The charge transport layer
is substantially nonabsorbing to visible light or radiation in the
region of intended use, but is electrically "active" in that it
allows the injection of photogenerated holes from the
photoconductive layer, or photogenerating layer, and allows these
holes to be transported through itself to selectively discharge a
surface charge on the surface of the active layer.
[0057] The thickness of the continuous charge transport overcoat
layer selected depends upon the abrasiveness of the charging (bias
charging roll), cleaning (blade or web), development (brush),
transfer (bias transfer roll), and the like in the system employed,
and can be up to about 10 microns. In embodiments, this thickness
for each layer is from about 1 to about 5 microns. Various suitable
and conventional methods may be used to mix, and thereafter apply
the overcoat layer coating mixture to the photoconductor. Typical
application techniques include spraying, dip coating, roll coating,
wire wound rod coating, and the like. Drying of the deposited
coating may be effected by any suitable conventional technique,
such as oven drying, infrared radiation drying, air drying, and the
like. The dried overcoating layer of this disclosure should
transport holes during imaging and should not have too high a free
carrier concentration.
[0058] The overcoat can comprise the same components as the charge
transport layer wherein the weight ratio between the charge
transporting small molecules, and the suitable electrically
inactive resin binder is, for example, from about 0/100 to about
60/40, or from about 20/80 to about 40/60.
[0059] Examples of components or materials optionally incorporated
into the charge transport layers or at least one charge transport
layer to, for example, enable excellent lateral charge migration
(LCM) resistance include hindered phenolic antioxidants, such as
tetrakis methylene(3,5-di-tert-butyl-4-hydroxy
hydrocinnamate)methane (IRGANOX.RTM. 1010, available from Ciba
Specialty Chemical), butylated hydroxytoluene (BHT), and other
hindered phenolic antioxidants including SUMILIZER.TM. BHT-R,
MDP-S, BBM-S, WX-R, NW, BP-76, BP-101, GA-80, GM and GS (available
from Sumitomo Chemical Company, Ltd.), IRGANOX.RTM. 1035, 1076,
1098, 1135, 1141, 1222, 1330, 1425WL, 1520L, 245, 259, 3114, 3790,
5057 and 565 (available from Ciba Specialties Chemicals), and ADEKA
STAB.TM. AO-20, AO-30, AO-40, AO-50, AO-60, AO-70, AO-80 and AO-330
(available from Asahi Denka Company, Ltd.); hindered amine
antioxidants such as SANOL.TM. LS-2626, LS-765, LS-770 and LS-744
(available from SNKYO CO., Ltd.), TINUVIN.RTM. 144 and 622LD
(available from Ciba Specialties Chemicals), MARK.TM. LA57, LA67,
LA62, LA68 and LA63 (available from Asahi Denka Co., Ltd.), and
SUMILIZER.TM. PS (available from Sumitomo Chemical Co., Ltd.);
thioether antioxidants such as SUMILIZER.TM. TP-D (available from
Sumitomo Chemical Co., Ltd); phosphite antioxidants such as
MARK.TM. 2112, PEP-8, PEP-24G, PEP-36, 329K and HP-10 (available
from Asahi Denka Co., Ltd.); other molecules, such as
bis(4-diethylamino-2-methylphenyl)phenylmethane (BDETPM),
bis-[2-methyl-4-(N-2-hydroxyethyl-N-ethyl-aminophenyl)]-phenylmethane
(DHTPM), and the like. The weight percent of the antioxidant in at
least one of the charge transport layers is from about 0 to about
20, from about 1 to about 10 weight percent, or from about 3 to
about 8 weight percent.
[0060] Primarily for purposes of brevity, the examples of each of
the substituents, and each of the components/compounds/molecules,
polymers, (components) for each of the layers, specifically
disclosed herein, are not intended to be exhaustive. Thus, a number
of components, polymers, formulas, structures, and R group or
substituent examples, and carbon chain lengths not specifically
disclosed or claimed are intended to be encompassed by the present
disclosure and claims. Also, the carbon chain lengths are intended
to include all numbers between those disclosed or claimed or
envisioned, thus from 1 to about 20 carbon atoms, and from 6 to
about 36 carbon atoms includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, up to 36, or more. At least one refers, for
example, to from 1 to about 5, from 1 to about 2, 1, 2, and the
like. Similarly, the thickness of each of the layers, the examples
of components in each of the layers, the amount ranges of each of
the components disclosed and claimed is not exhaustive, and it is
intended that the present disclosure and claims encompass other
suitable parameters not disclosed or that may be envisioned.
[0061] The following Examples are being submitted to illustrate
embodiments of the present disclosure. These Examples are intended
to be illustrative only, and are not intended to limit the scope of
the present disclosure. Also, parts and percentages are by weight
unless otherwise indicated. A Comparative Example and data are also
provided.
Comparative Example 1
[0062] There was prepared a photoconductor with a biaxially
oriented polyethylene naphthalate substrate (KALEDEX.TM. 2000)
having a thickness of 3.5 mils, and thereover, a 0.02 micron thick
titanium layer was coated on the biaxially oriented polyethylene
naphthalate substrate (KALEDEX.TM. 2000). Subsequently, there was
applied thereon, with an extrusion coater (Hirano web coater), a
hole blocking layer solution containing 50 grams of 3 aminopropyl
triethoxysilane (.gamma.-APS), 41.2 grams of water, 15 grams of
acetic acid, 684.8 grams of denatured alcohol, and 200 grams of
heptane. This layer was then dried for about 1 minute at
120.degree. C. in a forced air dryer. The resulting hole blocking
layer had a dry thickness of 500 Angstroms. An adhesive layer was
then deposited by applying a wet coating over the blocking layer,
using an extrusion coater, and which adhesive contained 0.2 percent
by weight based on the total weight of the solution of the
copolyester adhesive (ARDEL D100.TM. available from Toyota Hsutsu
Inc.) in a 60:30:10 volume ratio mixture of
tetrahydrofuran/monochlorobenzene/methylene chloride. The adhesive
layer was then dried for about 1 minute at 120.degree. C. in the
forced air dryer of the coater. The resulting adhesive layer had a
dry thickness of 200 Angstroms.
[0063] A photogenerating layer dispersion was prepared by
introducing 0.45 gram of the known polycarbonate IUPILON 200.TM.
(PCZ-200) weight average molecular weight of 20,000, available from
Mitsubishi Gas Chemical Corporation, and 44.65 grams of
tetrahydrofuran (THF) into a 4 ounce glass bottle. To this solution
were added 2.4 grams of hydroxygallium phthalocyanine (Type V) and
300 grams of 1/8 inch (3.2 millimeters) diameter stainless steel
shot. This mixture was then placed on a ball mill for 3 hours.
Subsequently, 2.25 grams of PCZ-200 were dissolved in 46.1 grams of
THF, and added to the hydroxygallium phthalocyanine dispersion.
This slurry was then placed on a shaker for 10 minutes. The
resulting dispersion was, thereafter, applied to the above adhesive
interface with an extrusion coater. A strip about 10 millimeters
wide along one edge of the substrate web bearing the blocking layer
and the adhesive layer was deliberately left uncoated by any of the
photogenerating layer material to facilitate adequate electrical
contact by the ground strip layer that was applied later. The
photogenerating layer was dried at 120.degree. C. for 1 minute in a
forced air oven to form a dry photogenerating layer of
hydroxygallium phthalocyanine Type V and PCZ-200 with a weight
ratio of about 47/53, and having a thickness of 0.8 micron.
[0064] The resulting imaging member web was then overcoated with
two charge transport layers. Specifically, the photogenerating
layer was overcoated with a first pass charge transport layer (the
bottom layer) in contact with the photogenerating layer. The bottom
layer of the charge transport layer was prepared by introducing
into an amber glass bottle in a weight ratio of 1:1
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine
and MAKROLON.RTM. 5705, a known polycarbonate resin having a
molecular weight average of from about 50,000 to about 100,000,
commercially available from Farbenfabriken Bayer A.G. The resulting
mixture was then dissolved in methylene chloride to form a solution
containing 15 percent by weight solids. This solution was applied
on the photogenerating layer to form the bottom layer coating that
upon drying (120.degree. C. for 1 minute) had a thickness of 14.5
microns. During this coating process, the humidity was equal to or
somewhat less than 15 percent.
[0065] The bottom layer of the charge transport layer was then
overcoated with a second pass top layer. The charge transport layer
solution of the top layer was prepared by introducing into an amber
glass bottle in a weight ratio of 0.35:0.65
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1 '-biphenyl-4,4'-diamine
and MAKROLON.RTM. 5705, a known polycarbonate resin having a
molecular weight average of from about 50,000 to about 100,000,
commercially available from Farbenfabriken Bayer A.G. The resulting
mixture was then dissolved in methylene chloride to form a solution
containing 15 percent by weight solids. The resulting top layer
solution was applied on the bottom layer of the charge transport
layer to form a coating that upon drying (120.degree. C. for 1
minute) had a thickness of 14.5 microns. During this coating
process, the humidity was equal to or somewhat less than 15
percent.
Example I
[0066] A photoconductive member was prepared by repeating the
process of Comparative Example 1 except that there was included in
the photogenerating layer dispersion 5 weight percent of the
vulcanized fatty ester ADDITIN.RTM. RC8000, which contained
approximately 20 weight percent sulfur, and which vulcanized fatty
ester was obtained from RheinChemie with the ratio of
hydroxygallium phthalocyanine to the polycarbonate resin to the
vulcanized fatty ester being 44.8/50.5/4.7 in THF. The resulting
dispersion was, thereafter, applied on the adhesive layer with an
extrusion coater. The resulting member with the vulcanized fatty
ester photogenerating layer was dried at 120.degree. C. for 1
minute in a forced air oven to form a dry photogenerating layer of
hydroxygallium phthalocyanine Type V, PCZ-200 and the fatty ester
with a weight ratio of about 44.8/50.5/4.7, and having a thickness
of 0.8 micron.
Example II
[0067] A number of xerographic photoconductors member are prepared
by repeating the process of Example I except that there is selected
in place of the fatty ester ADDITIN.RTM. RC8000, 10 weight percent
of ADDITIN.RTM. R4410 which contains approximately 9.5 weight
percent sulfur content, ADDITIN.RTM. R4412-F which contains
approximately 12.5 weight percent sulfur content, ADDITIN.RTM.
R4417 which contains approximately 17.5 weight percent sulfur
content, ADDITIN.RTM. RC2515 which contains approximately 15 weight
percent sulfur content, ADDITIN.RTM. RC2526 which contains
approximately 26 weight percent sulfur content, ADDITIN.RTM.
RC2810-A which contains approximately 10 weight percent sulfur
content, ADDITIN.RTM. RC2814-A which contains approximately 14
weight percent sulfur content, or ADDITIN.RTM. RC2818-A which
contains approximately 16 weight percent sulfur content, all
obtained from RheinChemie.
Electrical Property Testing
[0068] The above prepared photoconductor devices of Comparative
Example 1 and Examples I were tested in a scanner set to obtain
photoinduced discharge cycles, sequenced at one charge-erase cycle
followed by one charge-expose-erase cycle, wherein the light
intensity was incrementally increased with cycling to produce a
series of photoinduced discharge characteristic curves from which
the photosensitivity and surface potentials at various exposure
intensities are measured. Additional electrical characteristics
were obtained by a series of charge-erase cycles with incrementing
surface potential to generate several voltage versus charge density
curves. The scanner was equipped with a scorotron set to a constant
voltage charging at various surface potentials. The devices were
tested at surface potentials of 400 volts with the exposure light
intensity incrementally increased by means of regulating a series
of neutral density filters; the exposure light source was a 780
nanometer light emitting diode. Xerographic simulation was
completed in an environmentally controlled light tight chamber at
ambient conditions (40 percent relative humidity and 22.degree.
C.).
[0069] Similar PIDC curves were obtained for the above
photoconductors. Thus, incorporation of the vulcanized fatty ester
into the photogenerating layer had substantially no negative impact
on the electrical properties of the photoconductors.
Ghosting Measurements
[0070] When a photoconductor is selectively exposed to positive
charges in a number of known xerographic print engines, some of
these charges may enter the photoconductor and manifest themselves
as a latent image in the next printing cycle. This print defect can
cause a change in the lightness of the half tones, and is commonly
referred to as a "ghost" that is generated in the previous printing
cycle.
[0071] An example of a source of the positive charges is the stream
of positive ions that may be emitted from the transfer corotron.
Since the paper sheets are situated between the transfer corotron
and the photoconductor, the photoconductor is shielded from the
positive ions from the paper sheets. In the areas between the paper
sheets, the photoconductor is fully exposed, thus in this paper
free zone the positives charges may enter the photoconductor. As a
result, these charges cause a print defect or ghost in a half tone
print when changing to a larger paper format that covers the
previous paper free zone.
[0072] In the ghosting test, the photoconductors were electrically
cycled to simulate continuous printing. At the end of every tenth
cycle known, incremental positive charges were injected. In the
follow-on cycles, the electrical response to these injected charges
were measured in a known electrical test fixture, and then
translated into a rating scale.
[0073] The electrical response to the injected charges in the above
known xerographic print engine and in the electrical test fixture
resulted in a drop in the surface potential. This drop was
calibrated to colorimetric values in the prints generated, and they
in turn were calibrated to a ranking scale of an average rating of
at least two observers. On this scale, 1 refers to no observable
ghost, and values of 7 or above refer to a very strong ghost. The
functional dependence between the change in surface potential and
the ghosting scale is slightly supra-linear, and may in first
approximation be linearly scaled. The ghosting tests were completed
under severe stress conditions, for example, actuators in the print
engine and in the test fixture are set in a manner that have the
potential to arrive at unacceptable ghosting.
[0074] Using a sputterer with a % inch diameter and a 150 .ANG.
thickness, gold dots were deposited onto the top charge transport
layer of the photoconductors in the above Comparative Example 1 and
Example I. The photoconductors were dark rested (in the absence of
light) for at least two days at 22.degree. C. and 50 percent RH to
allow relaxation of the surfaces.
[0075] Subsequently, the above electroded photoconductor devices
(gold dots on charge transport layer surfaces) were then cycled in
a test fixture that injected positive charges through the gold dots
with the methodology described above. The change in surface
potential was then determined for injected charges of 27
nC/cm.sup.2. This value was selected to be larger than typically
expected in the above xerographic print engine to generate strong
signals. Finally, the changes in the surface potentials were
translated into ghost rankings by the aforementioned calibration
curves. This method was repeated four times for each
photoconductor, and then the averages were calculated. Typical
standard deviation of the mean tested on numerous devices was about
0.35.
[0076] The ghosting ratings are reported in Table 1 that follows.
The Example I photoconductor exhibited an about 50 percent lower
ghosting than the Comparative Example 1 photoconductor. Thus, the
incorporation of the vulcanized fatty ester into the
photogenerating layer reduced ghosting.
TABLE-US-00001 TABLE 1 Ghosting Grade Comparative Example 1 7.8
Example I 4.2
[0077] The claims, as originally presented and as they may be
amended, encompass variations, alternatives, modifications,
improvements, equivalents, and substantial equivalents of the
embodiments and teachings disclosed herein, including those that
are presently unforeseen or unappreciated, and that, for example,
may arise from applicants/patentees and others. Unless specifically
recited in a claim, steps or components of claims should not be
implied or imported from the specification or any other claims as
to any particular order, number, position, size, shape, angle,
color, or material.
* * * * *